The AC is not factory installed but is factory air. I would guess it was done at the same time the color was changed and the interior changed out. It was built 05/09/68. I have had the compressor replaced but still have the original and the "muffler" if someone wants to go "original". As I stated in one of my posts, I also replaced the side mirrors (Classic Industries). There was a right side mirror on the car but I couldn't adjust it to see anything. I still have those too. The dual exhaust was not on the build sheet either as well as the rear manual antenna but both appear to be "Factory equivalent". The exhaust has the transverse resonator with the dual tipped pipes coming off to either side. Everything else matches the build sheet exactly. I have a picture of the engine compartment at the time I got the car showing the "factory" air system which I will post separately.